Preparation of deuterated



United States Patent ()fiice 3,132,188 Patented May 5, 1964 Thisinvention relates to the preparation of deuterated aromatic materialsand is more particularly concerned with a single step method ofpreparing high purity deuterated benzene.

Preparation of deuterobenzene has been accomplished usually by thedecomposition of Grignard reagents with heavy water. In this method,half the valuable deuterium atoms go into a generally not wanted Mg(OD)Also the method requires tedious work-up and difiicult separation of thedesired deuterooenzene.

It has now been found that deuterobenzene or its lower alkyl derivativesmay be readily prepared by (a) the reaction of an appropriate pyridinehydrohalide with an appropriate water-soluble alkali metal tetraphenylboron in the presence of heavy water (D (b) the removal of unreactedheavy water, (0) the decomposition of the resulting complex by heat and(d) the recovery of high purity deuterated benzene from the reactionmixture.

Appropriate pyridines have the formula:

IlydroX wherein X is a halogen, either chlorine, bromine or iodine,hydro is hydrogen or deuterium and R and R are hydrogen or lower alkylgroups containing up to 3 carbon atoms. Appropriate water-soluble boroncompounds have the formula:

AlkB

wherein Alk is lithium, sodium, potassium, cesium, rubidium or ammoniumand R and R are hydrogen or lower alkyl groups containing up to 3 carbonatoms. Since the lithium and sodium salts are more soluble in D 0, theyare preferred.

The appropriate pyridine salt and alkali metal tetraphenyl boron arecontacted in heavy water. A precipitate will ordinarily form.Equimolecular quantities of the pyridine and boron material are usuallyemployed, however, other ratios can be used if desired. Sufiicient heavywater is usually employed to have complete solution of the startingmaterials, thereby avoiding contamination of the reaction product.

After the precipitate has formed, the unreacted heavy water is removed,as by evacuating the reaction vessel, centrifugation, decantation, etc.,and the precipitate thereafter heated to between about 50 and 150degrees centigrade, thereby to distill the deuterated benzene from thereaction mixture. Monodeuterobenzene thus prepared has a high degree ofpurity and uses the heavy water in good efiiciency.

The following examples are given for the purposes of illustration andare not to be construed as limiting the invention thereto.

Example 1 Pyridine hydochloride (1.18 parts) was dissolved in 3 parts ofheavy water (D 0). Sodium tetraphenyl boron (3.48 parts) was dissolvedin 20 parts of D 0. The two resulting solutions were mixed to produce adense white precipitate, probably (C H ND)+(B (C H Excess D 0 wasremoved by evacuating the reaction vessel and the vessel thereafterheated to about degrees centigrade. A distillate was collected in acondenser and receiver. Infrared analysis of the distillate showed thematerial to be pure deuterated benzene (C H D). The yield was 0.51 partor 62.5 percent of theoretical.

Example 2 In a manner similar to that of the foregoing example pyridinedeuteroor hydrobromide, pyridine deuteroor hydriodide, or pyridinedeuterochloride may be substituted for the pyridine hydrochloridespecifically shown. Similarly, Z-methylpyridine, 2-ethylpyridine,2-propylpyridine, 2-isopropylpyridine, S-methylpyridine,3-ethylpyridine, 3- propylpyridine, 3-isopropylpyridine,4-methylpyridine, 4- ethylpyridine, 4-propylpyridine,4-isopropylpyridine, 2,6- dimethylpyridine, 2,6-diethylpyridine,2,6-dipropylpyridine, 2,6-diisopropylpyridine, 2,4-dimethylpyridine,2,4- diethylpyridine, 2,4-dipropylpyridine, 2,3-dimethylpyridine,2,5-dimethylpyridine, 3-methyl-6-ethylpyridine, etc. may be substitutedfor the pyridine specifically shown. Also, potassium, lithium, cesium orrubidium may be substituted for the sodium specifically shown. Each ofthe above substitutions will give results similar to those shown inExample 1. Similarly the phenyl group may be replaced by 2-, 3- or4-tolyl; 2-, 3- or 4-ethylphenyl; 2-, 3- or 4-propylphenyl; 2-, 3- or4-isopropylpheny1; 2,3-, 2,4-, 2,5-, 2,6-, or 3,4-xylyl;2-methyl-3-ethylphenyl; Q-methyl- 3-propylphenyl;2-methyl-3-isopropylphenyl-; 2,3-, 2,4-, 2,5-, 2,6-, or3,4-diethylphenyl; etc. to prepared alkyl substituted deuterobenzene.For example, sodium tetra (2- tolyl) boron will produceortho-deuterotoluene; sodium tetra (2-ethyl-4-propylphenyl) boron willproduce l-deutero-2-ethyl-4-propylbenzene; etc.

Various modifications may be made in the present invention withoutdeparting from the spirit or scope thereof and it is to be understoodthat I limit myself only as defined in the appended claims.

I claim:

1. The process which comprises contacting, in the presence of deuteriumoxide, a pyridine hydrohalide having the formula:

O C Hifill HydroX with an alkali metal tetraphenyl boron having theformula:

at a temperature between about 50 and about 150 degrees 7 centigrade,and separating a product having the formula: H R

wherein R and R have the hereinbefore assigned values and D isdeuterium.

2. The process which comprises contacting, in the presence of deuteriumoxide, a pyridine hydrohalide having the formula:

R C R X X C O la X H llydrox with an alkali metal tetraphenyl boronhaving the formula:

H H R Alk B wherein R and R have the hereinbefore assigned values and Dis deuterium.

3. The process which comprises contacting, in the presence of deuteriumoxide, pyridine hydrochloride with sodium tetraphenyl boron; heating theprecipitate thus formed at a temperature between about 50 and about 150degrees centigrade, and separating a monodeuterobenzene 25 from thereaction mixture.

No references cited.

1. THE PROCESS WHICH COMPRISES CONTACTING, IN THE PRESENCE OF DEUTERIUIMOXIDE, A PYRIDINE HYDROHALIDE HAVING THE FORMULA: